PITTSFIELD -- A city man who sold a semi-automatic rifle to a police informant in 2011 was sentenced to up to three years in state prison after pleading guilty to four charges on Tuesday in Berkshire Superior Court.

Sergio M. Ponce, 27, of Memorial Drive also pleaded guilty in a separate but related case in which, while under indictment, he made threatening comments on Facebook to the police informant who is in hiding in another state.

According to Assistant Berkshire District Attorney Gregory Barry, Ponce sold a Russian-made SKS-45 semiautomatic rifle stuffed into a guitar case along with 70 rounds of ammunition to an informant for $460 on Nov. 8, 2011. The deal was caught on audio and video by the Berkshire County Drug Task Force, who had set up the controlled buy.

The weapon was stolen from a storage facility in Stephentown, N.Y., and was one of a cache of 15 weapons taken in an August 2011 heist.

On Tuesday, Ponce pleaded guilty to improper sale of a firearm, illegal ownership of a firearm, possession of ammunition without a firearm identification card, and receiving stolen property over $250.

Ponce was scheduled to take a plea in the case last month, but changed his mind at the last minute with the intention of going to trial. In the intervening time he was charged with witness intimidation after posting statements on his Facebook account about the police informant, calling him "dead man walking," posting the informant's new address and announcing when the informant would be back in Berkshire County to testify.

The prosecutor said the informant had moved "down South" for his protection because he is a witness in a number of drug cases, besides being involved in Ponce's case. Barry did not name the state where the informant now lives.

Ponce pleaded guilty to felony witness intimidation in the second case.

Judge John A. Agostini sentenced Ponce to a total of at least 2 1/2 years and no more than three years in state prison on all charges. His decision was in line with the joint recommendation between Ponce's attorney, David Pixley, and the DA's Office.